Sustained exposure to that concentration of PM 2.5 is equivalent to smoking 40 cigarettes a day, said Sarath Guttikunda, the director of Urban Emissions, an independent research group.

On this basis, I did some calculations.

There were 180 countries in attendance, each comprising three delegates, and with other accredited attendees it is reported that around 1,500 were there. Over 8 days that means that the COP7 contingent 'smoked' between them the equivalent of around 480,000 fags!

Yet while waiting for three and a half hours for my pass to enter the venue, I could count on the fingers of one hand the number of delegates - you know, the ones who panic about a few wisps of smoke or vapour - worried enough about the danger to take precautions in the form of a mask or other prevention measure. Just saying.

I took some video and pictures while I was there and the boy P has edited it into a concise one minute film. It's a taste of the city under the smog; enjoy.